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Due to its rarity, astronomers are calling the 2017 phenomenon the Great American Eclipse.

Here are seven things to know about the big summer event:

When is it?

The Great American Eclipse will cross the U.S. on Aug. 21, and will begin in Oregon at 10:15 a.m. local time (so, 1:15 p.m. EST). The eclipse’s path of totality will cut a 60-mile-wide arc across the country and end in South Carolina about an hour and a half later.

Whether or not you’re inside the path of totality will determine what you see in the sky. If you’re outside the path, you’ll likely see a partial (not total) eclipse.

To determine the most accurate eclipse path, according to Wright, you have to figure out where the moon’s shadow will fall on the Earth’s surface, which requires taking into account the elevation differences on both the moon and Earth’s surfaces, he told Space.com.

Using elevation data from NASA’s Shuttle Radar Topography Mission, the locations of the Earth, moon and sun at each line of latitude or longitude and how long it takes sunlight to travel to the moon and down to Earth, Wright was able to compute where exactly the eclipse will cross and for how long.

How to find out what the eclipse will look like from where you live

Scientists at the University of California, Berkeley, teamed up with Google to create a simulator that shows you what the sky will look like wherever you are.

All you have to do is type in your hometown or zip code and the simulator will tell you how much of the sun will be blocked by the moon, how the sun will travel across the sky over a three-hour period on Aug. 21 and what time to watch.

“There are lots of online animations of the 2017 eclipse, but you can’t use them like ours to get a sense of the full experience, including your surroundings. Our simulation is closer to what one might experience in a planetarium show,” the UC Berkeley scientists said.

The tool could also help people figure out where to get the best “total solar eclipse experience,” the scientists said.

This simulator is part of the Eclipse Megamovie Project, a Google-Berkeley collaboration aimed at collecting and stitching together thousands of photos of the Aug. 21 eclipse taken by volunteer photographers around the country.

Even if you don’t plan on traveling or making your way outdoors for the great eclipse, NASA will be hosting an Eclipse Megacast across multiple programming venues, including NASA TV, YouTube, UStream and more. Local and national television stations will likely pick the Megacast up as well.

If you want to know how far you’ll have to travel from wherever you are to catch the total solar eclipse, this Google simulator will show you.

Just type in your zip code or city and the simulator will tell you how much of the sun will be blocked by the moon, how the sun will travel across the sky over a 3-hour period on Aug. 21 and what time to watch.